The ratio of the lengths of corresponding sides of two similar triangles is 7:10. The smaller triangle has an area of 63 cm2. What is the area of the larger triangle?

70 cm2

630 cm2

90 cm2

128.6 cm2

Question

The ratio of the lengths of corresponding sides of two similar triangles is 7:10. The smaller triangle has an area of 63 cm2. What is the area of the larger triangle?
		
70 cm2
		
630 cm2
		
90 cm2
		
128.6 cm2

crashonce · Answer

Alright to do this question you need to know this simple formula:
$$\frac{ l1^2 }{ l2^2 } = \frac{ A1 }{ A2 }$$
where l1 and l2 are the sides of the triangles and A1 and A2 are the areas

anonymous · Answer

Okay so it would be 90??

crashonce · Answer

so that means that $$\frac{ 7^2 }{ 10^2 } = \frac{ 63 }{ A2 }$$

crashonce · Answer

no

crashonce · Answer

using the formula i just typed in you can see the LHS will be 49/100 and the RHS will be 63/A2
Therefore, simplifying, we get 49A2 = 6300
THerefore A2= 128.6
D is the answer

anonymous · Answer

Oh thanks, sorry I had to go eat dinner.

crashonce · Answer

np